| HOME SCHEDULE AUTHOR INDEX SUBJECT INDEX |
|
(606) SPERM TRAINS AND MATING BEHAVIOR IN WOOD MICE OF THE GENUS Apodemus. Dvorakova, Katerina1, Stopka, Pavel2, 1 Charles University of Prague, Prague, Czech Republic2 Charles University of Prague, Prague, Czech Republic ABSTRACT- There is evidence of possible correlation between mating behaviour, sperm morphology and sperm behaviour in the female reproductive tract prior to fertilization. As previously shown in A. sylvaticus (Moore et al. 2002), cooperation between spermatozoa of an individual confer a significant advantage for fertilization, where inter-male sperm competition is intense. In our study we aimed to focus on three other species of rodent genus Apodemus; A. flavicolis, A. microps, A. agrarius versus A. sylvaticus, whose either promiscuous or monogamous mating behaviour has already been demonstrated (Stopka et al. Unpublished). We placed motile spermatozoa from the cauda epididymis of adult males of selected species into mouse in vitro fertilization medium, and compared sperm behaviour of individual species. Surprisingly, despite monogamous or polygamous mating behaviour, sperm of all the above species rapidly aggregated into motile clumps (10-50 cells) and as well as in A. sylvaticus, they formed, within 2-5 minutes, large motile trains of spermatozoa consisting of hundreds of cells. However, there were differences between the trains of each species in size, and way of cell-cell coupling. This may point to another aspect, besides mating behaviour that may be involved in building up a mechanism for successful sperm delivery to the egg. These unique and organized aggregations can significantly increase sperm progressive motility. A detailed study of the main cytoskeletal proteins, using immunofluorescent methods, together with confocal microscopy, shows that in sperm-sperm binding especially protein actin plays an important role. According to in vitro experiments, we speculate that the viscous environment of the female reproductive tract may have played a crucial role in the evolution of sperm behaviour. Disintegration of motile sperm trains was associated with the majority of spermatozoa undergoing a premature acrosome reaction (AR). However, the mechanism, which triggers this premature AR, remains to be determined. To conclude, it is likely that a myriad of changes in social behaviour of particular species were not accompanied by changes in sperm behaviour, but instead they retained original ancestral tactics typical for the genus Apodemus. KEY WORDS: mating behaviour, actin, sperm morphology, Apodemus |
